Effects of volume loading on strain rate and tissue Doppler velocity imaging in patients with idiopathic dilated cardiomyopathy

BACKGROUND: Strain rate is a promising echocardiographic technique which adds further information to that obtained with two-dimensional echocardiography and tissue Doppler imaging (TDI). The present study aimed to evaluate the effects of acute isotonic volume expansion on left ventricular function in patients with idiopathic dilated cardiomyopathy (DCM) utilizing TDI and strain rate measurements. METHODS: Ten patients with DCM and a left ventricular ejection fraction (LVEF) </= 40% underwent two-dimensional echocardiography during volume expansion (0.9% NaCl; 0.25 ml/kg/min for 120 min). Peak systolic tissue velocity and peak systolic strain rate were measured at baseline and at the end of volume loading. RESULTS: Mean LVEF was 32 +/- 9% at baseline and remained unchanged after volume loading. Similarly, peak systolic velocity was 2.21 cm/s at baseline and remained unchanged after volume expansion. By contrast, peak systolic strain rate significantly reduced from -1.08 +/- 0.37/s to -0.76 +/- 0.12/s (P < 0.05). CONCLUSIONS: In patients with DCM, peak systolic strain rate significantly reduces with volume loading in the absence of change in LVEF or peak systolic velocities at TDI. Because strain rate is a relative load-independent index of systolic function, the reduction observed is probably related to the decrease in left ventricular systolic performance that follows volume loading in heart failure patients. Thus, peak systolic strain rate appears to be more useful than TDI velocities to evaluate left ventricular dynamics during volume loading in patients with depressed left ventricular function.